In computing, hypertext is a user interface paradigm for displaying documents which, according to an early definition (Nelson 1970), "branch or perform on request." Hypertext is a way of organizing material that attempts to overcome the inherent limitations of traditional text and in particular its linearity. The prefix hyper- (Modern Greek term for over or beyond) signifies the overcoming of such constraints. The most frequently discussed form of hypertext document contains automated cross-references to other documents called hyperlinks. Selecting a hyperlink causes the computer to load and display the linked document.

A document can be static (prepared and stored in advance) or dynamically generated (in response to user input). Therefore, a well-constructed hypertext system can encompass, incorporate or supersede many other user interface paradigms like menus and command lines, and can be used to access both static collections of cross-referenced documents and interactive applications. The documents and applications can be local or can come from anywhere with the assistance of a computer network like the Internet. The most famous implementation of hypertext is the World Wide Web.

The term "hypertext" is often used where the term hypermedia might seem appropriate; the two have always been synonymous but "hypertext" is grammatically simpler.

A very good software for creating hypertext documents, both on the Web and on CD, is HyperPublish

Foreshadowing hypertext was a simple technique used in various reference works (dictionaries, encyclopedias, etc.), consisting of setting a term in small capital letters, as an indication that an entry or article existed for that term (within the same reference work). Sometimes the term would be preceded by a pointing hand dingbat, or an arrow. In addition to such manual cross-references, there were experiments with various methods for arranging layers of annotations around a document. The most famous example is the Talmud.

The point of hypertext is to deal with the problem of information overload. All of the persons mentioned below were obsessed with the realization that humanity is simply drowning in information, so that, too often, decision makers keep making foolish decisions and scientists inadvertently duplicate existing work (e.g., the belated rediscovery of Gregor Mendel's work).

In the early 20th century, two visionaries attacked the cross-referencing problem through proposals based on labor-intensive brute force methods. Paul Otlet proposed a proto-hypertext concept based on his monographic principle in which all documents would be decomposed down to unique phrases stored on index cards. In the 1930s, H.G. Wells proposed the creation of a World Brain. For reasons of cost, neither proposal got very far.

Therefore, all major histories of hypertext start with 1945, when Vannevar Bush wrote an article in The Atlantic Monthly called "As We May Think," about a futuristic device he called a Memex. He described the device as a mechanical desk linked to an extensive archive of microfilms and able to display books, writings or any document from the library, and further able to automatically follow references from any given page to the specific page referenced.

Most experts do not consider the Memex to be a true hypertext system. However, the story starts with the Memex because "As We May Think" directly influenced and inspired the two American men generally credited with the invention of hypertext, Ted Nelson and Douglas Engelbart.

Nelson coined the words "hypertext" and "hypermedia" in 1965 and helped Andries van Dam develop the Hypertext Editing System in 1968 at Brown University; Engelbart had begun working on his NLS system in 1962 at Stanford Research Institute, although delays in obtaining funding, personnel and equipment meant that its key features were not completed until 1968. That year, Engelbart demonstrated a hypertext interface to the public for the first time, in what has come to be known as "The Mother of All Demos".

After funding for NLS slowed to a trickle in 1974, progress on hypertext research nearly came to a halt. During this time, the ZOG at Carnegie Mellon started as an artificial intelligence research project under the supervision of Allen Newell. Only much later would its participants realize that their system was a hypertext system. ZOG was deployed in 1980 on the U.S.S. Carl Vinson and later commercialized as Knowledge Management System.

The first hypermedia application was the Aspen Movie Map in 1977.

The early 1980s saw a number of experimental hypertext and hypermedia programs, many of whose features and terminology were later integrated into the Web. However, none of these systems achieved widespread success or name recognition with consumers.

Guide was the first hypertext system for personal computers, but it was not very successful. Guide was quite expensive and difficult to use, as it had originally been developed for UNIX workstations and was subsequently ported to DOS. It was immediately eclipsed by HyperCard.

In August 1987, Apple Computer revealed its HyperCard application for its Macintosh line of computers at the MacWorld convention in Boston, Massachusetts. HyperCard was an immediate hit and helped to popularize the concept of hypertext with the general public (although as Jakob Nielsen later pointed out, it was technically a hypermedia system because its hyperlinks originated only from regions on the screen). The first hypertext-specific academic conference also took place that year.

Meanwhile, Nelson had been working on and advocating his Xanadu system for over two decades, and the commercial success of HyperCard stirred Autodesk to invest in his revolutionary ideas. The project limped on for four years without ever releasing a complete product, before Autodesk pulled the plug in the midst of the 1991-1992 recession.

In 1980, Tim Berners-Lee created ENQUIRE, an early hypertext database system, somewhat like a wiki. In the late 1980s, Berners-Lee, then a scientist at CERN, invented the World Wide Web to meet the demand for automatic information sharing between scientists working in different universities and institutes all over the world. Early in 1993, the National Center for Supercomputing Applications (NCSA) at the University of Illinois released a first version of their Mosaic browser to replace the two existing, somewhat deficient web browsers: one that ran only on NeXTSTEP and one that was minimally user-friendly. Mosaic ran in the X Window System environment, popular in the research community, and offered usable window-based interaction. It allowed images as well as text to anchor hypertext links, and it incorporated other Internet protocols, including Gopher protocol. Web traffic exploded from only 500 known web servers in 1993 to over 10,000 in 1994 after the release of browser versions for both the PC and Macintosh environments.

All the earlier hypertext systems were overshadowed by the success of the World Wide Web, even though it lacks many features of those earlier systems such as typed links, transclusion and source tracking.

A very good software for creating hypertext documents, both on the Web and on CD (with full text search capability), is HyperPublish